Memory mapped IO tracing found in arch/x86/Kconfig.debug

Help text

Mmiotrace traces Memory Mapped I/O access and is meant for
debugging and reverse engineering. It is called from the ioremap
implementation and works via page faults. Tracing is disabled by
default and can be enabled at run-time.

See Documentation/tracers/mmiotrace.txt.
If you are not helping to develop drivers, say N.

Help text

Mmiotrace traces Memory Mapped I/O access and is meant for
debugging and reverse engineering. It is called from the ioremap
implementation and works via page faults. Tracing is disabled by
default and can be enabled at run-time.

See Documentation/trace/mmiotrace.txt.
If you are not helping to develop drivers, say N.